Virtual structure formations of cooperating UAVs using wind-compensation command generation and generalized velocity obstacles

This paper describes two algorithms that can be utilized in tandem to direct a group of cooperating vehicles into time-varying formations using virtual structures as reference trajectories. The first algorithm is a command generation method to achieve high-precision position control in the presence of wind, and the second algorithm provides flight command overrides to avoid collisions. The command generation algorithm, which was verified in UAV flight demonstrations, is a wind-compensating flight control method wherein roll and airspeed commands are generated to steer each UAV toward a future position within the virtual structure. This algorithm provides a geometrically exact solution to achieve a desired location in the future in the presence of a spatially-uniform, time-invariant wind. In flight demonstrations, four vehicles were shown to achieve tight virtual structure formations despite the presence of significant winds. The second algorithm, demonstrated using a numerical simulation, provides active collision avoidance between members of the virtual structure using flight command overrides based on generalized velocity obstacles.